Usama ibn Zayd

Usama ibn Zayd (615-) was the grandson of Prophet Muhammad and a general of the Rashidun Caliphate, leading an army since the age of 17 or 18.

Biography
Usama ibn Zayd was the son of Prophet Muhammad's freed slave Zayd ibn Harithah and was considered to be Muhammad's grandson; his father was adopted by Muhammad. He fought for the first time in the 627 Battle of the Trench and the 630 Battle of Hunayn, and later fought under Muhammad and commanded an army at the age of 17 or 18. He lost his father in the September 629 Battle of Mu'tah, with Theodorus Heraclius defeating the Muslims. After the death of Muhammad in 632, Usama ibn Zayd launched an invasion of al-Sham (Syria), and he was the first general to defeat the Roman Byzantine Empire.